Question

1. ABCD is a cyclic quadrilateral. If AB Il CD
then prove that BC = AD.​

Answer 1

ABCD is a cyclic quadrilateral.

So ∠A + ∠C = 180 …….(i)

Since AD ∥ BC

So ∠B + ∠A = 180 ……….(ii)

From (i) & (ii)

∠A + ∠C = ∠B + ∠A

⇒ ∠C = ∠B

Or ∠B = ∠C.

Hence proved.